For background on recording an electrocardiograph in digital format using a portable device reference is made to U.S. Pat. No. 4,920,489.
A typical prior art approach for measuring oxygen saturation uses a large nonportable bedside unit, or a portable unit with recording capabilities limited to oxygen saturation. These devices typically display a measurement in a hospital or laboratory setting. Such devices, when portable, are typically limited to short duration recording or recording only of oxygen saturation.
It is an important object of the invention to provide methods and means for recording a wide spectrum of electrocardiographic signal waveforms simultaneously with high resolution oxygen saturation data signals.
Another object of the invention is to achieve the preceding object while allowing the user to see both electrocardiographic and oxygen saturation data synchronized in time to facilitate a more accurate diagnosis regarding the condition of the patient.
Still another object of the invention is to achieve one or more of the preceding objects while recording all the recorded data, including the electrocardiographic and oxygen saturation data signals, on a single removable memory device to facilitate easy transfer of the recorded data to another location.
Still a further object of the invention is to achieve one or more of the preceding objects while allowing evaluation of the signal to ensure high quality recording.
Yet another object of the invention is to achieve one or more of the preceding objects while providing identification information recording in the removable memory to reduce error and facilitate tracking of data.
Still another object of the invention is to achieve one or more of the preceding objects while detecting pacemaker activity in the same recording as the oxygen saturation signal.